Gas compressor



A. POLIANSKY GAS COMPRESSOR Jan. 24, 1956 6 Sheets-Sheet 1 Filed Jan.16, 1952 INVENTOR. ALETAH 0R0 PoL/A n SKY II/II A. POLIANSKY GASCOMPRESSOR Jan. 24, 1956 6 Sheets-Sheet 2 Filed Jan. 16, 1952 INVENTOR.ALEJAN DRo Poumy SK y Jan. 24, 1956 A. POLIANSKY 2,732,124

GAS COMPRESSOR Filed Jan. 16, 1952 6 Sheets-Sheet 3 INVENTOR. ALETAN 0R0POL/ANSK y Jan. 24, 1956 A. POLIANSKY 2,732,124

GAS COMPRESSOR Filed Jan. 16, 1952 6 Sheets-Sheet 4 F' v '1 8 a 711g. 62 mfiififlfiWm 5? 2a n Am J H mm 5 46a IN VEN TOR.

ALEJ'AN DRO PouA m S)\ 1;

Jan. 24, 1956 A-. POLIANSKY 2,732,124

GAS COMPRESSOR Filed Jan. 16, l952 6 Sheets-Sheet 5 Jig.- 10

INVENTOR. ALEJANORQ Pom/m SK 7 Jan. 24, 1956 A. POLJANSKY 2,732,124

I GAS COMPRESSOR Filed Jan. 16, 1952 6 Sheets-Sheet 6 INVENTOR. ALEJANDO PoLIAH SKY BY J United States Patent GAS COMPRESSOR AlejandroPoiianslry, Buenos Aires,

My present invention relates to certain new and use ful improvements inair or gas compressors and more particularly refers to an improved gascompressor of the type having at least one pair of compressor headscombined, within one and the same casing, with electric means fordriving the pistons of the compressor heads.

The main object of the invention is to provide an improved gascompressor, whereon the linear movements of at least one armatureattracted alternately by two electro-magnets are used for operating thepistons of at least one pair of compressor heads, with the advantageousresult that the usually employed electric motor and crank may bedispensed with and that the compressor structure is considerablysimplified.

One object of the invention is to provide an improved gas compressor,wherein spring means are provided in connection with the pistons of thecompressor heads and are so arranged that they at least in part mitigatethe rough movements of the armatures attracted by the electro-magnets,with the advantageous result that said spring means at the same timerecover energy and assist in returning the armatures to their neutralposition and in reducing the gap between the armature and the core ofeach electro-magnet, thereby rendering the driving mechanism moreefficient.

Another important object of the invention consists in providing animproved gas compressor, wherein each compressor head comprises acomposite piston so constructed and arranged that the same in itsgas-compressing stroke provides for the formation on the bottom of thecompressor cylinder of a gas cushion capable of acting as an efficientshock absorber for the piston and the whole compressor structure, withthe advantageous result that at the same time an efficient and simpleoperator of the usual non return valve of the pressure cham her isobtained.

Still another not less important object of the invention is to providean improved gas compressor, wherein automatic switch means are providedin connection with the electro-magnets for alternately energizing thesame in dependence upon the movements of their armatures, with theadvantageous result that the operation of the electro-magneticallydriven compressor is absolutely reliable.

A further important object of the invention is to provide an improvedgas compressor, wherein the automatic switch means for controlling theelectro-magnets include electric resistance means so arranged as toreduce the energizing current of the electro-magnets as well as to avoidthe necessity of interrupting the electric circuit for saidelectromagnets, but to keep it closed by way of an electric resistanceand to thereby eliminate the disadvantageous formation of sparks, withthe additional advantageous result that the reduction of the energizingcurrent at the same time assists in mitigating the rough attractionproduced by the electro-magneic force.

According to another feature of the invention, the improved gascompressor may include, ,in connection 2,732,124 Patented Jan. 24, 1956"ice with the switch means, a synchronous motor for controlling theswitch means associated with pairs of electro-magnets of the compressor,with the advantageous result that the electro-magnets are energized anddeenergized in due course for ensuring a correct and efficient operationof the compressor-driving mechanism.

According to an important feature of the invention, the improved gascompressor comprises automatic switch means under the control of the gascompressed by the compressor in combination with a control by springmeans, with the advantageous results that the pistons of the compressorheads are always stopped in their working strokes at a certain distancefrom the bottom of the compressor cylinders by controlling therespective electric circuits in relation to the counter-pressure, withthe advantageous result that usual pistons may be successfully employed.

In accordance with still another feature of the invention, the improvedgas compressor comprises at least one pair of compressor heads and atleast one pair of electro-magnets for operating the pistons of saidcompressor heads through lever means connected to or forming parts ofthe armatures of said electro-magnets. In the case of providing at leasttwo pairs of compressor heads, the arrangement of the compressor may besuch as to produce both low and high pressure, in which case thecompressor casing is subdivided by a partition wall into a low pressuresection and a high pressure section.

With these objects and advantageous features in view, the presentinvention comprises the arrangement, combination and construction ofparts as will be hereniafter fully described with particular referenceto the accompanying drawings showing by way of examples only somepreferred embodiments of the invention.

On the accompanying drawings:

Figure l is a cross-sectional view of a gas compressor according to theinvention, with two compressor heads arranged in one and the same wallof the compressor casing;

Figure 2 is a longitudinal sectional view of a compressor head accordingto the invention;

Figure 3 shows in a cross-sectional view another em bodiment of thecompressor, wherein two compressor cylinders act upon a common pressurechamber;

Figure 4 is a sectional detail view of the pressure chamber of theembodiment of Figure 3;

Figure 5 is a horizontal sectional view of a compressor of two stages,low and high pressure; in the upper portion of this figure theelectro-rnagnets have been omitted Whereas in the lower portion thereofthe springs on the piston rods are not shown for reasons of clearness;

Figure 6 is a vertical somewhat schematical sectional view along theline 66 of Figure 5;

Figures 7 and 8 are views similar to Figures 5 and 6, showing a simplerembodiment of a low and high pressure compressor;

Figure 9 is a schematic view showing a pair of opposite electro-magnetsand the switch device controlling said electro-magnets, this switchdevice including electric resistance means for avoiding the formation ofsparks;

Figure 10 is a sectional view showing an embodiment of switch deviceaccording to Figure 9;

Figure 11 is a circuit showing the electric connection for theelectro-magnets of the compressor according to Figures 5 and 6, whereinthe electro-magnets are connected in two groups one for low pressure andthe second one for high pressure.

In these views, like reference numerals indicate like or correspondingparts and for reasons of clearness the means for fastening the componentparts of the device, the supports of the electro-magnets, the fixingmeans for the cover of the casing, for the compressor heads, the

compressing piston 8 inlet and outlet ports of the gas, the electricconnections of the electro-magnets, have been omitted, because theseelements are quite known and may be arranged in accordance with therequirements of each case.

Referring to the accompanying drawings, and more particularly to Figures1 and 2, the invention is shown as incorporated in a compressor havingtwo alternately operating compressor heads.

The compressor according to this embodiment comprises a casing 1, ofwhich form integral parts the cylinders 2 and 2a of the two compressorheads, the pressure chambers 3 and 3a of these compressor heads beingfirmly secured to the free open ends of the cylinders 2 and 2a,respectively. Both the cylinder 2, 2a and the pressure chambers 3, 3a ofeach compressor head are conveniently provided with cooling ribs asshown. The wall of they pressure chambers 3, 3a adjacent the open end ofthe compressor cylinders 2, 2a has a gas-inlet opening, which iscontrolled by a valve 4 under the pressure of a coil spring 5; the valve4 being guided by means of its rod 6 in a corresponding cavity providedin a removable plug 7 (Figure 2).

The compressor cylinder 2 of each compressor head has a composite pistonconsisting of a hollow cylindrical (Figure 2) and a solid push member 9movably arranged within the hollow piston 8. This hollow piston 8 isprovided with usual piston rings for making a tight seal between thewalls of the piston 3 and cylinder 2. The top wall of the hollow piston8 has a central gas-outlet opening 16 in front of the gas-inlet openingof the pressure chamber 3, said opening constituting a valve seat forco-operating with the solid push member 9 acting as a valve for closingsaid opening 10 under the pressure of a coil spring surrounding thepiston rod 11 which extends through the central perforation of a disc 13removably secured to the lower open end of the hollow piston 8 andprovided with gas-inlet holes 14. For the purpose of efficiently actingas a valve, the push member 9 has a truncated conical top portionprovided with a layer of rubber or like sealing material 15, thearrangement being such that in its closing position the top of thepiston 9 projects slightly beyond the upper rim of the gas-outletopening 10. In view of that this opening 10 has a diameter larger thanthat of the gas-inlet opening of the chamber 3, the push member 9 at thesame time acts as a counter-valve for said gas-inlet opening.

In Figure 2, the composite piston at the compressor head has been shownat the end of its compressing stroke. When the piston rod 11 is nowwithdrawn, the member 9 opens the gas-outlet opening 10, compresses thespring around the rod 11 and withdraws the hollow piston 8. During thismovement, the gas to be compressed passes through the inlet openings 14and the outlet opening 19 into the free space within the cylinder 2above the top wall of the hollow piston 3. Now, for effecting thecompression of gas, the push member 9 first closes the gasoutlet opening10 and then pushes the hollow compressing piston 8 forwards, therebycompressing the gas and cansing it to pass through the gas-inlet openingof the pressure chamber 3 as soon as the gas pressure surpasses thepressure of the spring-loaded valve 4. Before the top of the compressingpiston can get in touch with the wall of the pressure chamber 3, the topof the member 9 closes the gas-inlet opening of the pressure chamber 3,thereby trapping certain quantity of gas within the cylinder 2 whichconstitutes an effective bufier preventing the hollow piston 8 fromshocking with the adjacent wall of the pressure chamber 3. Thus anoiseless operation of compressing cylinder is ensured.

By virtue of this construction of the compressor heads and otherfeatures to be described later, the compressor according to the presentinvention, for its operation, may use the electro-magnetic force whichas is well known acts in a rough manner rendering the same unsuitablefor mechanical purposes.

The electro-magnetic mechanism for operating the compressor according tothe invention, may be designed in different manner. A relatively simpleembodiment has been shown in Figure 1. The same comprises twoelectromagnets formed by the cores 16, 16a and the magnetic coils 17,17a. As soon as one or another of these coils is energized, their coresattract their respective armatures constituted in this case by the arms18, 18a of a lever pivoted at 19. If desired, the armatures may beformed by special bodies secured to said lever arms. The eta-operatingsurfaces of the armatures and of the cores are conveniently chamfered asindicated at 20 for thus obtaining a smaller gap between said surfacesand a greater effect of electro-rnagnetic attraction.

The free ends of the lever arms 18, 18a are pivotally connected in anysuitable known manner with the free ends of the piston rods 11 of thecomposite pistons 8, 9 (Figure 2). The piston rods 11 are surrounded bycoil springs 21 which at one end abut against a disk or like stop 22secured to the respective piston rod, and at the opposite end abutagainst a rod 23 secured to a support 24 provided in the casing It. Thesprings 21 initiate the return stroke of the pistons in the moment therespective electro-magnets are deenergized thereby recovering energy andreducing the gap between the armature and the cores of theelectromagnets, trying to keep these armatures in their neutralposition;

For alternately energizing the two electro-magnets in the correctmoments, the present invention provides automatic switch means whichwill'be described later.

For absorbing or damping the noise likely to be produced by the freeends of the lever arms 18, 13a, rubber pads 25 or the like may beprovided.

A modified embodiment of the electro-magnetic compressor according tothe invention has been shown in Figtires 3 and 4, wherein two compressorcylinders 2, 2a act upon a common pressure chamber 3. The constructionof the compressor cylinder with their composite pistons is identicalwith that as described with reference to Figure 2. The operation of thepistons differs from that shown in Figure 1 by that instead of a doublearm lever, two one-arm levers 18, 1.8a are used, to which the pistonrods 11 are pivotally connected at 26. The piston rods project beyondtheir pivots 26 for extending with their free ends into small cylinders25 having gas-inlet orifices and acting as pneumatic shock absorbers.

In this embodiment, as shown in Figure 3, the electromagnets are formedeach by a U-shaped core 16, 16a and two coils 17, 17' and 17a, 17'aarranged on the legs of the cores in such a manner that they terminatewithin said coils with charnfered end surfaces. The armatures 18', 18apivotally connected with the respective levers 18, 18a are also U-shapedand have correspondingly chamfered le ends which extend into thecavities left by the cores 16, 16a within the coils 17, 17', 17a, 17'a.This arrangement is advantageous insofar as by two coils in eachelectro-magnet with less quantity of copper one obtains the same numberof windings, less ohmic losses and larger heat-dissipating surface, andby means of the gap between armature and core arranged within the coils,a more efficient attraction of the armature is ensured by adding thesolenoid attraction, beside this there being less dispersion of themagnetic lines of forces and an increase of the armature mass.

The free ends of the levers l8 and are interconnected by means of a rod27 freely supported in a lug 28 or the like, at each side of which therod 27 is surrounded by a coil spring 21. These springs abut at one endagainst the lug 28 and at the opposite end against a stop means 29,constituted for instance by a nut and counternut as shown. The springs21 act in the same manner as described with reference to those 21 ofFigure l.

The levers .18, 18a are further interconnected by a rod 3%) whichcomprises a triangular projection 31. This projection co-operates with aspring-loaded pin 32 movably disposed within a corresponding recessprovided in a slidable contact-carrier 33, the contacts 34 of whichco-operate with fixed contacts 35. This assembly -35 constitutes anautomatic switch the operation of which will be described later.

Another embodiment of the compressor according to the invention has beenshown in Figures 5 and 6. This embodiment represents a double compressorfor producing low and high pressure. The casing 1 is subdivided by apartition wall 36 into a low pressure section and a high pressuresection, each of these sections comprising four compressor heads 2, 2a,2b, 2c, which are of the same construction as that described withreference to Figure 2. The piston rods 11 of the compressor heads areconnected at their free ends with the levers 18, 18a carrying armaturebodies 18' and 13'a for being acted upon by the electro-magnets 16, 17and 16a, 17a, i. e. each lever is operated by two oppositeelectro-magnets. As has been clearly shown in Figure 6, the co-operatingsurfaces of the cores 16, 16a and armatures 18' and 18'a are at leastpartly chamfered. In this embodiment, the springs 21 on the piston rods11 abut at one end against the connecting members of said rods with thelevers 18, 18a and at the opposite end against rods 37 which at the sametime constitute supporting members for the cores 16, 16a.

In this embodiment, the pressure chambers of the compressor heads of thelow pressure section are conveniently communicated with the gas inletsof the high pressure section of the compressor (not shown).

The embodiment as shown in Figures 7 and 8 represents a simplifiedconstruction of the embodiment of Figures 5 and 6 and differs therefromonly in that the compressor sections of low and high pressure compriseeach but one pair of compressor heads. Consequently, in view of thatlike parts are indicated by the same reference numerals a detaileddescription of this further embodiment is not required.

Before describing the operation of the switch devices, it may be pointedout that in any case the stationary contacts are not connected with thecoils of the electromagnets to which they are secured, but areconnectedin the case of Figure 3to the opposite electromagnet, and-inthe case of various pairs of electro-inagnets-are connected to thatelectro-magnet which is the next one to worlr.

Referring back to Figure 3, in the position of the contact-carrier 33 asshown on the drawing, the electric circuit is closed for theelectro-magnet 16, 17 which thus energized attracts the armature lever18. This motion of the lever 18 is transmitted to the rod 3%) and theprojection 3i of the latter displaces the pin 32 against the pressure ofits spring. In the moment the vertex of the triangular projection 31 haspassed the pin 32 i. e. in the moment of the attraction of the armaturelever 18 by the electro magnet 16, 17 being completed, said pin underthe pressure of its spring moves outwards and thereby displaces thecontact-carrier 33 to the right until closing the circuit for theelectro-magnet 16a, 17a which thus energized attracts the armature lever13a. The rod 30 again moves to the right and the contact-carrier 33 tothe left. Thus the automatic switch never remains in a neutral position,but always ensures the operation of the different electro-mag ets in thecorrect moment.

The present invention, as been already pointed out, makes use of theelectromagnetic force-attraction of armatures by eiectro-magnets foroperating a gas compressor. it is well known that the attraction ofarmatures by electroanagnets is instantaneous and the motion of thearmatures consequently is so rough and quick that it is mechanicallydirTicult to transmit said motion and take profit thereof for directlyoperating a mechanical. In order to counteract this roughness of motion,it has here inbet'ore proposed to provide the piston rods 11 withsprings 21 and to employ a special piston capable of providing for theformation of a shock-absorbing gas cushion 6 on the bottom of thecompressor cylinder 2. in addition to these measures, the presentinvention provides another one consisting in a control of the electriccurrent for energizing the electro-magnets in relation to the pressureproduced by the compressor.

Another disadvantage of the electro-magnets consists in that, wheninterrupting the energizing current which produces a magnetic field, andelectric spark will be formed when the magnetic field disappears. inorder to avoid the formation of sparks, according to this invention, Ireduce the energizing current by means of a first resistance and inaddition hereto 1 do not interrupt the circuit of the energizingcurrent, but deenergize the electro-magnets by means of a secondresistance.

The two afore-mentioned features are incorporated in the switcharrangement as shown in Figures 9 and 10 of the accompanying drawings.

In Figure 9, the reference numerals 16 indicate a pair U-shaped coremembers and 17 two pairs of electric coils in an arrangement similar tothat shown in Figure 7. The electro-magnets 16, 17 act upon a common H-shaped armature 18 provided with a rigid arm 38 which constitutes theoperating member for the switch device, in this case, for a movablecontact bridge carrier 51, which carries four contact bridges 52, 53,54, Sci-two pairs for each eiectro-magnet-and which is slidably mountedon a rod 56 (Figure 1') between the two opposite portions 33, 33a of acomposite contact carrier, each portion of which carries five contacts5'7, 58, 59, 6t), 61 and 57a, 53a, 5%, 69a, tile, respectively.

The portion (Figure 9) of the contact carrier has been shown in its endposition for energizing the lower electromagnet. The operation of theswitch device is now as follows: The armature l8 attracted by said lowerelectic-magnet moves downwards and the arm 38 moves the contact bridgecarrier in the same direction. Thereby the contact 59 is opened and theelectric current is caused to pass through the resistance R1, wherebyits voltage is reduced. While continuing its movement, the contactbridge carrier 51, instead of interrupting the current for the lowerelectro-magnet, interconnects the contacts 57 and 58 and therebyestablishes the connection with the resistance R2, so that the latter,with the same voltage as reduced by the resistance R1, is connected inparallel with the coils A7 of the lower electro-magnet. Hereupon, whilethe contact bridge carrier 51 still continues moving downwards, thecircuit is interrupted between the contact 52 and the contact bridge 63,whereby the coil 17 of the lower electroiagnet is deenergized by thatthe resistance R absorbs the whole voltage and the current of the selfinduction of the coil thus avoiding the formation of a spark. At thismoment, the lower electro-magnet is inoperative; the compressing pistonconnected to the armature 18 has completed its gas-compressing stroke,The contact bridge carrier 51, however, continues its movement due, onthe one hand, to the elasticity of the arm 33 and, on the other hand; tothe co-operation of the spring-loaded pin 32 with the tapered projection31 of said contact bridge carrier 51, as has been described in detailwith reference to Figure 3, and by virtue of this further movement thecontact bridge carrier 51 completes the circuits corresponding to theupper electro-magnet by means or" the contacts of the contact carrierportion 33a, attracting the armature 18 in upward direction and movingthe arm 38 in the same direction. The contact bridge carrier 51,however, remains stationary until the arm 38 has moved over the freespace 62 which is substantially wider than the thickness of the arm 33,and starts moving as soon as the somewhat elastic arm 33 subdues theinertia of the mass of the contact bridge carrier 51 and the resistanceoffered by the spring-loaded pin 32. The elasticity of the arm 38assists in accelerating the contact closures between the contact bridgecarrier 51 and the contact carrier portion 33a. The succession ofcontact closures is identical to that as hereinbefore described; at

7 first the resistance Rla is connected, then the coil 17 of the upperelectro-magnet is connected in parallel with the resistance Ru, andfinally the said coil is deenergized by the resistance RZa as aforesaid.

In some cases, particularly in connection with relatively smallcompressors, the resistances R2 and R23, may be omitted if desired.

For the purpose of counteracting the rough movements caused by theattraction of the armature and of avoiding the noise likely to be causedby the pistons of the compres sor cylinders, the switch device ashereinbeforc scribed is advantageously combined with a pneumatic controldevice.

This device comprises a small cylinder 63 communicated by way of a pipe64 with the pressure chamber of one of the compressor heads of thecompressor, according to the invention, and a pair of opposite pistons65, 65a, the rods of which 66, 66a are rigidly connected to the contactcarrier portions 33, 33a. The cylinder 63 is provided with an attachment67 which extends between the opposite contact carrier portions 33, 33afor limiting their relative movement towards each other caused by thepressure of the springs 63, 68a.

With regard to this pneumatic control device, it will be readilyunderstood that when starting the operation of the compressor, therewill be no pressure at all supplied to the cylinder 63 and the contactcarrier portions 33, 33a will be under the pressure of the springs 63,65a and will be pressed against the attachment 67. The switch devicewill normally operate as above described.

As the pressure produced by the compressor increases, the pressure alsoincreases in the cylinder 63 and causes the pistons 65, 65a to moveoutwards and to move the contact carrier portions 33, 33a in the samedirection against the pressure of the springs 63, 68a. Thereby theperiods during which the contact bridges 52-54 maintain the contactsS761, 57a6lta closed, will be shortened.

As has been previously pointed out, in any case the switch device alwayscloses the electric circuit of the electro-magnet which is the next oneto work, and for the purpose of clearly explaining this detail, theFigure 11 shows a circuit diagram, wherein the four pairs of oppositeelectro-magnets are indicated at I-la, lIlIu, Ill-Illa, lVlVa. Figure llshows the arrangement of the electro-magnets in two groups, forinstance, one group for low pressure and the second one for highpressure.

Having reference to Figure ll, the conductors 41 of a source of electriccurrent are connected to a bipolar switch 42, indicating the referencenumeral 43 a pair of fuses for the protection of the compressor and 44 acondenser in parallel connection with the compressor for preventing thereaction load of the electro-magnets from excessively charging thedevice, whereas the numeral 50 indicates a connection to a distancecontrol, for the use of which the switch .2 must be an automatic switch.

The armature body 18 is shown between the co-operating electro-magnetsand for each pair of electro-magnets there is shown a contact-carrier33, the contacts 34 of which co-operate with the contacts secured toeach electro-magnet, this automatic switch acting in the same manner ashereinbeiore explained.

The electro-magnets I, la and II, Ila of one group may actsimultaneously with those IV, lVa and lllllla of the other group. Ineach group, the switches shown adjacent the electro-magnets I, II andIII, IV are in their circuit-closing position. For the purpose ofexplaining the operation of the electro-magnets, it is supposed thatonly the switches shown adjacent the electro-magnets II and III, are intheir circuit-closing position. Thus, the electric current entering byway of the conductor 45 reaches the first contact 35 on theelectro-magnets ll and Ill and as the contact-carrier 33 establishesconnections with the second contact 35 of said electro-magnets, the

electric circuit is closed by way of the conductors 46 for theelectro-magnets I and IV which thus energized attract their armatures18.-

The movements of these attracted armatures 18 move the switches adjacentthe electro-magnets I and IV to their circuit-closing position, so thatby way of the conductor 47 the electro-magnets Ila and Illa areenergized and produce the attraction of the armature 18 provided betweenthe electro-magnets II and Ila and those Ill and Illa. The movement ofthese armatures causes a circuit closure by the respective switches atthe contacts 35 on the electro-magnets Ila and Illa so that now by wayof the conductors 48 the electro-magnets Ia and lVa are energized whichin turn attract again the armature 18 between the electro-magnets I andla and those IV and IVa, with the result that then at the contacts 35 onthe electro-magnets la and lVtz the circuit is closed by way of theconductors 49 for the electro-magnets II and Ill and that the latterattract the armatures 13 situated between the electro-magnets ll and Ilaand those Ill and Illa. Thereby a complete cycle of operations hasfinished and the same is repeated again and again as long as electriccurrent is supplied to the device.

It will be understood that the arrangement of the stationary contacts 35on the electro-magnets is by way of example only and merely for notcomplicating the draw ing, and that any other place may be selected forthe arrangement of said contacts. The construction and arrangement ofthe automatic switches may also change and are by no means restricted tothe embodiment shown in Figure 3. In as far as the arrangement of theelectromagnets and their connection with the piston rods are concerned,the invention is not limited to the embodiments as shown in Figures 1,34, 5-6, 78, but that alterations and amendments may be introducedtherein and that finally in addition to the illustrated embodiments ofthe invention, the basic idea of the same may be carried into practicein other embodiments which, of course, have to be considered as fallingwithin the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. Gas compressor having a sealed casing with an entrance opening forthe gas to be compressed and at least one pressure chamber for receivingthe compressed gas, and comprising at least one pair of compressor headssecured to the walls of the compressor casing and communicated on theone hand with the interior of said casing and on the other hand withsaid pressure chamber, a non-return valve provided in the latter forcontrolling the communications between the compressor heads and thepressure chamber, a spring-loaded piston movably arranged in eachcompressor head and comprising an axially projecting front portion forprematurely closing the communication between the compressor head andthe pressure chamber to provide for the formation of a shockabsorbinggas cushion in said compressor head for said compressing piston, eachcompressing piston having a piston rod extending into the interior ofthe compressor casing, at least one pair of electromagnets fixedlyarranged within said compressor casing and formed by stationary coresand coils carried by leg portions of said cores and by armature bodiesmovably arranged in front of said cores for being attracted thereby in adirection substantially coaxial to said coils, lever means carrying saidarmature bodies and pivotally connected with said piston rods fortransmitting and increasing the oscillating movements of said armaturebodies to said compressing pistons, spring means secured to said pistonrods for mitigating the movements of said pistons at the end of theirworking strokes and for assisting the same in initiating their workingstrokes, and electric switch means including at least one contactcarrier movably arranged within the compressor casing for alternatelysupplying electric current to the coils of said electromagnets.

2. Gas compressor, according to claim 1, wherein each compressor head isprovided with a pressure chamber.

3. Gas compressor, according to claim 1, wherein each compressor headcomprises a composite piston formed by a hollow cylindrical piston bodyand a solid push member movably arranged within said hollow piston bodyand provided with a rod for operating the composite piston.

4. Gas compressor, according to claim 1, wherein the armature body ofeach electromagnet is carried by an individual lever.

5. Gas compressor, according to claim 1, wherein the armature bodies ofa pair of oppositely arranged electromagnets are carried by a commonlever.

6. Gas compressor, according to claim 1, wherein each compressor headcomprises a composite piston formed by a hollow cylindrical piston bodyand a spring-loaded push member within said hollow piston body foroperating the latter, said hollow piston body having end walls, one ofwhich is provided with a perforation for the passage of the rod of saidpush member and with a number of gas inlet openings, whereas itsopposite end wall is provided with a gas outlet opening in alignmentwith said perforation for the passage of the rod of said push member,which in turn is provided with a projecting portion for temporarilyclosing said gas outlet opening, and this gas outlet opening being ofsuch a diameter to permit said projecting portion to extend therethroughand to temporarily close the usual gas passage opening between thecompressor head and the pressure chamber.

7. Gas compressor, according to claim 1, wherein the cores of theelectromagnets and the armature bodies have charnfered cooperatingsurfaces.

8. Gas compressor according to claim 1, wherein the cores of theelectromagnets terminate within the coils of the latter and the armaturebodies comprise a projecting portion extending into the cavity formedwithin said coils.

9. Gas compressor according to claim 1, wherein the cores of theelectromagnets terminate within the coils of the latter and the armaturebodies comprise a projecting portion extending into the cavity formedwithin said coils.

10. Gas compressor according to claim 1, wherein the cores of pairs ofcooperating electromagnets are U-shaped and their legs terminate withinthe coils of said electromagnets, and the armature associated with saidpairs of electromagnets are also U-shaped and extend into the cavitiesformed within the coils of the pairs of cooperating electromagnets.

11. Gas compressor according to claim 1, wherein the cores of pairs ofcooperating electromagnets are U-shaped and their legs terminate withinthe coils of said electromagnets, and the armatures associated with saidpairs of electromagnets are also U-shaped and extend into the cavitiesformed within the coils of the ing electromagnets.

12. Gas compressor according to claim 1, wherein the said electricswitch means comprise a movable contact carrier including a movable,spring-loaded tapered member and a rod provided with a taperedprojection arranged in the path of said tapered member of the contactcarrier; conductor means for connecting the contacts of said contactcarrier with the terminals of the coils of electromagnets.

13. Gas compressor according to claim 1, wherein the said electricswitch means comprise a movable contact carrier including a movable,spring-loaded tapered member and a rod connected to the saidarmature-carrying lever means and provided with a tapered projectionarranged in the path of said tapered member of the contact carrier tomake the movements of the latter dependent upon the attraction byelectromagnets of said armature-carrying lever means and conductor meansfor connecting the contacts of said contact carrier with the terminalsof the coils of said electromagnets.

14. Gas compressor according to claim 1, wherein the said electricswitch means comprise a movable contact carrier including a movablespring-loaded tapered memher, a fixed rod provided with a taperedprojection arranged in the path of said tapered member of said contactcarrier; this contact carrier being provided with a pair of arms forbeing engaged by a projection of the armature means of theelectromagnets controlled by said contact carrier, and conductor meansfor connecting the contacts of said carrier with the terminals of thecoils of said electromagnets.

15. Gas compressor according to claim 1, wherein the said electricswitch means include a first resistance for reducing the energizingcurrent of an electromagnet and a second resistance for deenergizingsaid electromagnet without interrupting its feeding circuit and forthereby avoiding the formation of sparks in said electromagnet, andcontact means for successively connecting said resistances.

pairs of cooperat- Reierences Cited in the file of this patent UNITEDSTATES PATENTS 878,260 Watson Feb. 4, 1908 1,602,054 Stewart Oct. 5,1926 2,054,097 Replogle Sept. 15, 1936 2,596,943 Sheen May 13,19522,605,042 Reutter July 29, 1952 2,629,538 Replogle Feb. 24, 1953 FOREIGNPATENTS 464,565 Great Britain Apr. 20, 1937 890,926 France Feb. 22, 1944

